SofaKingA: It sounds like it is definitely a hardware issue on BB. If you think it is worth it, take it apart and make sure it is clean; if not the actual button may be broken, consider taking it to a BlackBerry repair shop or buying a new component from Horizon Wireless or another BlackBerry specialist.

Andrewer: Try a battery pull if you have not done so yet, if not also consider trying reinstalling the OS, it may need another chance to reinstall input drivers.